1. Field of the Invention
The present invention relates to a roof structure and, more specifically, to a retractable roof structure capable of being partially opened.
2. Description of the Prior Art
As is generally known, the buildings of stadiums for baseball games and for athletic sports are not provided with any roof in order that sporting events, such as baseball games and athletic sports, can be performed in an environment resembling the natural environment as close as possible. However, in such a conventional stadium, the sporting event is obliged to be postponed when it rains on the prearranged day or the sporting event is obliged to be interrupted when it starts raining while the sporting event is being performed.
Recently, all-weather stadiums have been proposed in order to eliminate the foregoing disadvantages of the conventional stadium. The pneumatic film roof structure, for instance, is one notable roof structure for an all-weather stadium. However, the pneumatic film roof structure has the following problems.
The pneumatic film roof structure has a roofing made of a synthetic resin film or the like, and is incorporated into the building of a stadium. In such a stadium, pressurized air having a pressure slightly higher than the atmospheric pressure is supplied into the sealed building. Therefore, the doorways of the building need to be formed in a complicated construction to prevent the leakage of the internal air. Furthermore, the pneumatic film roof structure makes the internal lighting and ventilation of the building difficult and spoils the pleasure of performing or watching the sporting event in a natural environment.
A partially retractable roof structure has been proposed in a copending U.S. application Pat. No. 882,979, which has a roof section comprising movable roof units capable of being moved along guide members for covering and uncovering an opening formed in a stationary roof unit, and capable of being retracted into the stationary roof unit.